The overall objective of this study is to determine the extent to which a growing tumor is able to ensure its own success by the release of antigen into the circulation and whether immunologic manipulations in this area can increase host resistance against the tumor. There is ample evidence that tumors release antigen from the cell surface and that this antigen forms complexes with existing antibody in the circulation. Although the respective roles of free antigen, antigen-antibody complex, or free antibody have been demonstrated in vitro, the role of these same materials in the host immune response in vivo is less clear. Therefore, the specific objectives of the project are to isolate tumor antigen and specific antibody from antigen-antibody complexes and to determine the effect these have on tumor growth. Long-term goals include development of radioassays for estimation of the rate of antigen production in vivo and monitoring the effect of tumor growth on the infusion of animals with antigen, antibody, or complexes. Resistance against tumor growth will be induced or increased by immunizing macrophages with soluble antigen in vitro and finally transferring immune cells to the intact animal. The ultimate goal of these experiments is to continue to look for new and rational models of immunotherapy based on better understanding of the effect of tumor growth on the immune response.